linux-kernel - Re: [PATCH] Bluetooth: Allow reset via sysfs

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Message-ID: <CABBYNZKDRm7vf1RewwW-+0fBwHTS0RXKqxNME_HpyB-q-mNLYQ@mail.gmail.com>
Date: Mon, 6 Jan 2025 11:29:06 -0500
From: Luiz Augusto von Dentz <luiz.dentz@...il.com>
To: Hsin-chen Chuang <chharry@...omium.org>
Cc: linux-bluetooth@...r.kernel.org, 
	chromeos-bluetooth-upstreaming@...omium.org, 
	Johan Hedberg <johan.hedberg@...il.com>, Marcel Holtmann <marcel@...tmann.org>, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] Bluetooth: Allow reset via sysfs

Hi Hsin-chen,

On Thu, Jan 2, 2025 at 10:21 PM Hsin-chen Chuang <chharry@...omium.org> wrote:
>
> Allow sysfs to trigger reset via the cmd_timeout function in hci device.
> This is required to recover devices that are not responsive from
> userspace.

Don't we have a similar control over USB to reset the device? I think
that would be better than introducing something btusb specific.

> Also remove the cmd timeout count in btusb since we only ever allow one
> command in flight at a time. We should always reset after a single
> command times out.
>
> Signed-off-by: Hsin-chen Chuang <chharry@...omium.org>
> ---
> This commit has been tested on a Chromebook by running
> `echo 1 > /sys/class/bluetooth/hci0/reset`
>
>  drivers/bluetooth/btusb.c | 10 ----------
>  net/bluetooth/hci_sysfs.c | 19 +++++++++++++++++++
>  2 files changed, 19 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/bluetooth/btusb.c b/drivers/bluetooth/btusb.c
> index 279fe6c115fac..a4810c77fa0da 100644
> --- a/drivers/bluetooth/btusb.c
> +++ b/drivers/bluetooth/btusb.c
> @@ -879,7 +879,6 @@ struct btusb_data {
>         int (*disconnect)(struct hci_dev *hdev);
>
>         int oob_wake_irq;   /* irq for out-of-band wake-on-bt */
> -       unsigned cmd_timeout_cnt;
>
>         struct qca_dump_info qca_dump;
>  };
> @@ -912,9 +911,6 @@ static void btusb_intel_cmd_timeout(struct hci_dev *hdev)
>         struct gpio_desc *reset_gpio = data->reset_gpio;
>         struct btintel_data *intel_data = hci_get_priv(hdev);
>
> -       if (++data->cmd_timeout_cnt < 5)
> -               return;
> -
>         if (intel_data->acpi_reset_method) {
>                 if (test_and_set_bit(INTEL_ACPI_RESET_ACTIVE, intel_data->flags)) {
>                         bt_dev_err(hdev, "acpi: last reset failed ? Not resetting again");
> @@ -997,9 +993,6 @@ static void btusb_rtl_cmd_timeout(struct hci_dev *hdev)
>
>         btusb_rtl_alloc_devcoredump(hdev, &hdr, NULL, 0);
>
> -       if (++data->cmd_timeout_cnt < 5)
> -               return;
> -
>         if (!reset_gpio) {
>                 btusb_reset(hdev);
>                 return;
> @@ -1044,9 +1037,6 @@ static void btusb_qca_cmd_timeout(struct hci_dev *hdev)
>                 return;
>         }
>
> -       if (++data->cmd_timeout_cnt < 5)
> -               return;
> -
>         if (reset_gpio) {
>                 bt_dev_err(hdev, "Reset qca device via bt_en gpio");
>
> diff --git a/net/bluetooth/hci_sysfs.c b/net/bluetooth/hci_sysfs.c
> index 4b54dbbf0729a..7bf2b10b0a7cf 100644
> --- a/net/bluetooth/hci_sysfs.c
> +++ b/net/bluetooth/hci_sysfs.c
> @@ -90,9 +90,28 @@ static void bt_host_release(struct device *dev)
>         module_put(THIS_MODULE);
>  }
>
> +static ssize_t reset_store(struct device *dev, struct device_attribute *attr,
> +                          const char *buf, size_t count)
> +{
> +       struct hci_dev *hdev = to_hci_dev(dev);
> +
> +       if (hdev->cmd_timeout)
> +               hdev->cmd_timeout(hdev);
> +
> +       return count;
> +}
> +static DEVICE_ATTR_WO(reset);
> +
> +static struct attribute *bt_host_attrs[] = {
> +       &dev_attr_reset.attr,
> +       NULL,
> +};
> +ATTRIBUTE_GROUPS(bt_host);
> +
>  static const struct device_type bt_host = {
>         .name    = "host",
>         .release = bt_host_release,
> +       .groups = bt_host_groups,
>  };
>
>  void hci_init_sysfs(struct hci_dev *hdev)
> --
> 2.47.1.613.gc27f4b7a9f-goog
>


-- 
Luiz Augusto von Dentz